27 - High Blood Pressure I Flashcards
(20 cards)
What is blood pressure?
Force of blood against artery walls as it circulates through body. Essential for distributing blood throughout the body
Blood pressure changes during the cardiac cycle. What is systolic pressure and diastolic pressure?
Systolic: maximum blood pressure during contraction of the ventricles
Diastolic: minimum pressure recorded just prior to the next contraction (ventricular relaxation)
Incidence of high BP increases or decreases with age?
increases
How is blood pressure primarily regulated?
By the sympathetic NS and the kidneys through their influence on cardiac output and peripheral vascular resistance
How to calculate blood pressure?
BP = Cardiac output x Peripheral vascular resistance
What is cardiac output? What is peripheral vascular resistance?
Amount of blood pumped out by each ventricle per minute
Resistance in the circulatory system that is used to create blood pressure
There are a few critical sites/mechanisms where drugs regulate blood pressure. What are they and how do drugs regulate these areas?
Heart: control how hard heart is pumping: beta blockers and diuretics
Resistance vessels: what is the heart pumping against: alpha blockers: NOT commonly used to treat BP
RAAS (renin-angiotensin-aldosterone system): regulates blood volume and peripheral resistance.
What are thiazides? What do they do for blood pressure?
diuretics: drugs that get rid of excess water in the body. They increase urine production in the kidneys, which lowers the pressure in the blood vessels
They do this by inhibiting the Na+/Cl_ cotransporter (NCC) in the renal distal convoluted tubule, increasing sodium and water excretion
What is the RAAS composed of?
kidneys, adrenal gland, vasculature
Adrenergic receptors are G-protein couple receptors and are an important target for regulating blood pressure. The two groups of adrenergic receptors are alpha and beta adrenergic receptors. Where are the beta receptors found>
Beta1 receptors are the predominant adrenergic receptor in the heart. These receptors are responsible for acceleration of heart rate and flight/fight response
Activation of these receptors causes bronchodilation (widening of the airways), enhancing blood flow to skeletal muscles during a fight or flight response
What are beta blockers
block action of endogenous catecholamines on beta adrenergic receptors, part of the sympathetic nervous
widely used in the treatment for hypertension
In vascular and bronchiolar smooth muscle, protein kinase A plays a key role in relaxation by inhibiting:
Myosin light chain kinase (MLCK). MLCK normally promotes contraction by phosphorylating myosin light chains, allowing smooth muscle contraction. PKA phosphorylates MLCK, reducing its activity, which prevents contraction and leads to smooth muscle relaxation
In vascular/bronchiolar smooth muscle, predominantly B2, key targets of PKA are:
Myosin light chain kinase this protein enables constriction of smooth muscle
Phosphorylation by PKA inhibits myosin light chain kinase: causes smooth muscle to relax (dilate bronchioles, dilate vessels)
In cardiac muscle, predominantly B1, key targets of PKA are:
L-type voltage-gated Ca2+ channels: PKA phosphorylation increases their activity, leading to more Ca2+ influx during depolarization, which strengthens contraction
Ryanodine receptors (RyR2): PKA enhances Ca2+ release from the sarcoplasmic reticulum (SR), increasing intracellular Ca2+ levels and boosting contraction strength
SECRA pumps: acts to transport calcium ions from the cytosol back to the sarcoplasmic reticulum (SR) following muscle contraction
Anti-hypertensive effects of beta blockers are mediated primary by:
1) decrease in cardias output by decreasing the heart rate and contractibility
2) inhibition of renin secretion
What do alpha adrenergic receptors do for BP?
not commonly used to treat high BP.
alpha1-receptors are the primary adrenergic receptors - vasoconstriction
They mediate their effects via inositol phospholipase (IP3) and diacylglycerol (DAG)
What does activation and inhibition of alpha 1 receptors cause?
Activation: vasoconstriction of arterioles
Inhibition: vasodilation of arterioles
What does activation and inhibition of beta 1 receptors cause?
Activation: increased cardiac contractility, rate
Inhibition: decreased cardias contractility, rate
What does activation and inhibition of beta receptors cause?
Activation: relaxation of airway, vascular smooth muscle
Inhibition: constriction of airway, vascular smooth muscle
What does positive inotropic and positive chronotropic effect mean?
Inotropic: factors that influence cardiac contractility
positive inotropic: increased heart contractibility
Chronotropic: factors that influence heart rate
positive chronotropic effect: increased heart rate
